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Topping Off Trump

Staff | September 28, 2010

Chicago— Concrete crews from James McHugh Construction Co. hauled up the final bucket of concrete to the top of Trump International Hotel & Tower Chicago in August, officially completing the 92nd floor of the tallest reinforced concrete building in the Western Hemisphere.

An American flag flapped in a light breeze atop the concrete bucket, which took 12 full minutes to haul via crane from ground level to the 1,170-foot top of the tower, which will be the second-tallest building in Chicago when complete. McHugh, the concrete contractor for the project, has been working with construction manager Bovis Lend Lease to erect the structure for The Trump Organization. Chicago's Skidmore, Owings & Merrill LLC is the project architect and engineer.

"This is quite a feat," said Dave Alexander, McHugh's senior vice president. "We've learned a lot about building tall in the process." Trump is the tallest building erected in the United States since Sears Tower, completed in 1974.

During September workers began attaching the architectural spire that will enable the building to reach its official height of 1,362 feet.

Since work on Trump began three years ago, McHugh has poured 180,000 cubic yards of concrete — 20 truckloads — and laid 25,000 tons of steel reinforcing bars to erect the tower. That equals enough concrete to build 10 medium-sized high-rises of 30 to 40 stories, according to Brett Szabo, McHugh's senior project manager.

Despite the building's size, McHugh worked on a rapid schedule, pouring a floor a week for the building's massive lower levels, and a floor every three days for the upper levels. To handle the volume of concrete and the extreme height, McHugh acquired a 680-horsepower Putzmeister concrete pump, one of the first of its kind in the United States, to drive the river of liquid concrete up through more than 1,700 feet of tubing known as slick lines and keep 35,000 pounds of material flowing through it. The pump could push more than 6,000 pounds of concrete to the top per minute, as opposed to 10-plus minutes per bucket via crane.

With the final floor poured, McHugh began removing one of the two Liebherr tower cranes on the site. The second crane will be removed after the spire is placed.

The wind and weather encountered building a super tall structure in Chicago posed its share of challenges to McHugh. Crews battled extreme cold, with temperatures more than 30 degrees colder than street level and winds that blew up to 30 mph harder than on the ground, while pouring the upper floors. A three-story-tall windscreen, which McHugh introduced for use in the United States, provided protection, and the team learned to demobilize quickly when wind gusts exceeded safe levels.